1. Field of the Invention
The present invention relates to air cycle systems, and more particularly, to an air cycle water producing machine.
2. Description of the Related Art
Air cycle air conditioners have been proposed for some years as an alternative to vapor-compression air conditioners in residential, commercial and automobile applications, see for example, U.S. Pat. Nos. 5,121,610 and 5,295,370. This is because they have several advantages over vapor-compression systems. Firstly, because the evaporators of vapor-compression heat pump devices operate at or near 0° C., their heating capacity is seriously impaired at low ambient temperatures, since they rely on heat transfer from ambient to the evaporator. Secondly, in cold weather ice forms on the evaporator heat transfer surfaces thereby increasing pressure losses and also reducing evaporator effectiveness. Thirdly, vapor-compression devices use chlorofluorocarbons (CFCs) as the refrigerant which presents manufacturing and maintenance problems with regard to refrigerant leakage, problems which are substantially reduced when air is used as the refrigerant. In addition, CFCs are known to have a harmful effect on the Earth's ozone layer and it is thought that they may also be contributing to global warming caused by the so-called greenhouse effect.
Despite these advantages, air cycle air conditioning systems have yet to make a significant impact on the residential, telecommunications and more particularly the automobile markets. This can be attributed to the fact that air cycle designs have been previously based on regenerative heat exchangers for improving the coefficient of performance (COP). However, the improvement is minimal when the increased losses due to the presence of the heat exchanger(s) are taken into account, and may also be seen as expendable when offset against the attendant increases in complexity, size and cost of the conditioning system.
For purposes of automobile and telecommunication applications, these prior art air conditioning systems have proven to be too large and or not sufficient. For systems utilizing CFCs, a condenser is required and placed in front of the automobile radiator. This increases the heat load for the entire cooling system of the engine. In addition, when Freon or other CFCs are used, these systems generally come with high maintenance costs. When using a straight air cycle air conditioning system that generally consists of a compressor, air to air or air to water heat exchanger and a cooling turbine, the advantage is that they are generally compact in nature and low in maintenance costs. However, similar to the CFC systems, the heat exchanger is disposed in front of the automobile radiator which inherently prevents the heat exchanger from enabling a reduction in the temperature of the compressed air below that of the outside air. Thus, in order to reach and air temperature close to 0° C. after the turbine, higher pressure is required in the compressor. This higher pressure requirement required significantly more power which takes away from the engine power provided to the automobile. In addition, since the air from the turbine is generally fed directly into the automobile cabin space, there is a high noise level associated with such systems.
In telecommunication systems, the size of the air conditioning unit is significant part of design considerations for rack and cabinet type systems. Therefore, an air cycle air conditioning system that operates efficiently and can be made small enough to fit within or on a telecommunications rack cabinet without consuming a large amount of valuable space would be desirable.
In addition, if for example you have air with 30° C. and 60% humidity, in order to cool this air from 30° C. to 0° C. requires approximately twice the amount of energy than otherwise required to cool dry 30° C. air to 0° C.